Remembering Jules Verne's enticing picture of life on the palatial Nautilus, I may as well admit that I was not prepared for a real submarine. My first impression, as I entered the hold, was that of discomfort and suffocation. I felt, too, that I was too close to too much whirring machinery. I gazed about curiously. On all sides were electrical devices and machines to operate the craft and the torpedoes. I thought, also, that the water outside was uncomfortably close; one could almost feel it. The Z99 was low roofed, damp, with an intricate system of rods, controls, engines, tanks, stop-cocks, compasses, gauges—more things than it seemed the human mind, to say nothing of wireless, could possibly attend to at once.

"The policy of secrecy which governments keep in regard to submarines," remarked the captain, running his eye over everything at once, it seemed, "has led them to be looked upon as something mysterious. But whatever you may think of telautomatics, there is really no mystery about an ordinary submarine."

I did not agree with our "Captain Nemo," as, the examination completed, he threw in a switch. The motor started. The Z99 hummed and trembled. The fumes of gasoline were almost suffocating at first, in spite of the prompt ventilation to clear them off. There was no escape from the smell. I had heard of "gasoline heart," but the odour only made me sick and dizzy. Like most novices, I suppose, I was suffering excruciating torture. Not so, Kennedy. He got used to it in no time; indeed, seemed to enjoy the very discomfort.

I felt that there was only one thing necessary to add to it, and that was the odour of cooking. Cooking, by the way, on a submarine is uncertain and disagreeable. There was a little electric heater, I found, which might possibly have heated enough water for one cup of coffee at a time.

In fact, space was economised to the utmost. Only the necessaries of life were there. Every inch that could be spared was given over to machinery. It was everywhere, compact, efficient—everything for running the boat under water, guiding it above and below, controlling its submersion, compressing air, firing torpedoes, and a thousand other things. It was wonderful as it was. But when one reflected that all could be done automatically, or rather telautomatically, it was simply astounding.

"You see," observed Captain Shirley, "when she is working automatically neither the periscope nor the wireless-mast shows. The wireless impulses are carried down to her from an inconspicuous float which trails along the surface and carries a short aerial with a wire running down, like a mast, forming practically invisible antennae."

As he was talking the boat was being "trimmed" by admitting water as ballast into the proper tanks.

"The Z99," he went on, "is a submersible, not a diving, submarine. That is to say, the rudder guides it and changes the angle of the boat. But the hydroplanes pull it up and down, two pairs of them set fore and aft of the centre of gravity. They lift or lower the boat bodily on an even keel, not by plunging and diving. I will now set the hydroplanes at ten degrees down and the horizontal rudder two degrees up, and the boat will submerge to a depth of thirty feet and run constant at that depth."

He had shut off the gasoline motor and started the storage-battery electric motor, which was used when running submerged. The great motors gave out a strange, humming sound. The crew conversed in low, constrained tones. There was a slightly perceptible jar, and the boat seemed to quiver just a bit from stem to stern. In front of Shirley was a gauge which showed the depth of submergence and a spirit-level which showed any inclination.

"Submerged," he remarked, "is like running on the surface under dense-fog conditions."

I did not agree with those who have said there is no difference running submerged or on the surface. Under way on the surface was one thing. But when we dived it was most unpleasant. I had been reassured at the start when I heard that there were ten compressed-air tanks under a pressure of two thousand pounds to the square inch. But only once before had I breathed compressed air and that was when one of our cases once took us down into the tunnels below the rivers of New York. It was not a new sensation, but at fifty feet depth I felt a little tingling all over my body, a pounding of the ear-drums, and just a trace of nausea.

Kennedy smiled as I moved about. "Never mind, Walter," he said. "I know how you feel on a first trip. One minute you are choking from lack of oxygen, then in another part of the boat you are exhilarated by too much of it. Still," he winked, "don't forget that it is regulated."

"Well," I returned, "all I can say is that if war is hell, a submarine is war."

I had, however, been much interested in the things about me. Forward, the torpedo-discharge tubes and other apparatus about the little doors in the vessel's nose made it look somewhat like the shield used in boring a tunnel under compressed air.

"Ordinary torpedo-boats use the regular automobile torpedo," remarked Captain Shirley, coming ubiquitously up behind me. "I improve on that. I can discharge the telautomobile torpedo, and guide it either from the boat, as we are now, or from the land station where we were last night, at will."

There was something more than pride in his manner. He was deadly in earnest about his invention.

We had come over to the periscope, the "eye" of the submarine when she is running just under the surface, but of no use that we were below. "Yes," he remarked, in answer to my half-spoken question, "that is the periscope. Usually there is one fixed to look ahead and another that is movable, in order to take in what is on the sides and in the rear. I have both of those. But, in addition, I have the universal periscope, the eye that sees all around, three hundred and sixty degrees—a very clever application of an annular prism with objectives, condenser, and two eyepieces of low and high power."

A call from one of the crew took him into the stern to watch the operation of something, leaving me to myself, for Kennedy was roaming about on a still hunt for anything that might suggest itself. The safety devices, probably more than any other single thing, interested me, for I had read with peculiar fascination of the great disasters to the Lutin, the Pluviose, the Farfardet, the A8, the Foca, the Kambala, the Japanese No 6, the German U3, and others.

Below us I knew there was a keel that could be dropped, lightening the boat considerably. Also, there was the submarine bell, immersed in a tank of water, with telephone receivers attached by which one could "listen in," for example, before rising, say, from sixty feet to twenty feet, and thus "hear" the hulls of other ships. The bell was struck by means of air pressure, and was the same as that used for submarine signalling on ships. Water, being dense, is an excellent conductor of sound. Even in the submarine itself, I could hear the muffled clang of the gong.

Then there were buoys which could be released and would fly to the surface, carrying within them a telephone, a light, and a whistle. I knew also something of the explosion dangers on a submarine, both from the fuel oil used when running on the surface, and from the storage batteries used when running submerged. Once in a while a sailor would take from a jar a piece of litmus paper and expose it, showing only a slight discolouration due to carbon dioxide. That was the least of my troubles. For a few moments, also, the white mice in a cage interested me. White mice were carried because they dislike the odour of gasoline and give warning of any leakage by loud squeals.

The fact was that there was so much of interest that, the first discomfort over, I was, like Kennedy, beginning really to enjoy the trip.

I was startled suddenly to hear the motors stop. There was no more of that interminable buzzing. The Z99 responded promptly to the air pressure that was forcing the water out of the tanks. The gauge showed that we were gradually rising on an even keel. A man sprang up the narrow hatchway and opened the cover through which we could see a little patch of blue sky again. The gasoline motor was started, and we ran leisurely back to the dock. The trip was over—safely. As we landed I felt a sense of gladness to get away from that feeling of being cut off from the world. It was not fear of death or of the water, as nearly as I could analyse it, but merely that terrible sense of isolation from man and nature as we know it.

A message from Burke was waiting for Kennedy at the wharf. He read it quickly, then handed it to Captain Shirley and myself.

Have just received a telegram from Washington. Great excitement at the embassy. Cipher telegram has been despatched to the Titan Iron Works. One of my men in Washington reports a queer experience. He had been following one of the members of the embassy staff, who saw he was being shadowed, turned suddenly on the man, and exclaimed, "Why are you hounding us still?" What do you make of it? No trace yet of Nordheim

BURKE.

The lines in Craig's face deepened in thought as he folded the message and remarked abstractedly, "She works all right when you are aboard." Then he recalled himself. "Let us try her again without a crew."

Five minutes later we had ascended to the aerial conning-tower, and all was in readiness to repeat the trial of the night before. Vicious and sly the Z99 looked in the daytime as she slipped off, under the unseen guidance of the wireless, with death hidden under her nose. Just as during the first trial we had witnessed, she began by fulfilling the highest expectations. Straight as an arrow she shot out of the harbour's mouth, half submerged, with her periscope sticking up and bearing the flag proudly flapping, leaving behind a wake of white foam.

She turned and re-entered the harbour, obeying Captain Shirley's every whim, twisting in and out of the shipping much to the amazement of the old salts, who had never become used to the weird sight. She cut a figure eight, stopped, started again.

Suddenly I could see by the look on Captain Shirley's face that something was wrong. Before either of us could speak, there was a spurt of water out in the harbour, a cloud of spray, and the Z99 sank in a mass of bubbles. She had heeled over and was resting on the mud and ooze of the harbour bottom. The water had closed over her, and she was gone.

Instantly all the terrible details of the sinking of the Lutin and other submarines flashed over me. I fancied I could see on the Z99 the overturned accumulators. I imagined the stifling fumes, the struggle for breath in the suddenly darkened hull. Almost as if it had happened half an hour ago, I saw it.

"Thank God for telautomatics," I murmured, as the thought swept over me of what we had escaped. "No one was aboard her, at least."

Chlorine was escaping rapidly from the overturned storage batteries, for a grave danger lurks in the presence of sea water, in a submarine, in combination with any of the sulphuric acid. Salt water and sulphuric acid produce chlorine gas, and a pint of it inside a good-sized submarine would be sufficient to render unconscious the crew of a boat. I began to realise the risks we had run, which my confidence in Captain Shirley had minimised. I wondered whether hydrogen in dangerous quantities might not be given off, and with the short-circuiting of the batteries perhaps explode. Nothing more happened, however. All kinds of theories suggested themselves. Perhaps in some way the gasoline motor had been started while the boat was depressed, the "gas" had escaped, combined with air, and a spark had caused an explosion. There were so many possibilities that it staggered me. Captain Shirley sat stunned.

Yet here was the one great question, Whence had come the impulse that had sent the famous Z99 to her fate?

"Could it have been through something internal?" I asked. "Could a current from one of the batteries have influenced the receiving apparatus?"

"No," replied the captain mechanically. "I have a secret method of protecting my receiving instruments from such impulses within the hull."

Kennedy was sitting silently in the corner, oblivious to us up to this point.

"But not to impulses from outside the hull," he broke in.

Unobserved, he had been bending over one of the little instruments which had kept us up all night and bad cost a tedious trip to New York and back.

"What's that?" I asked.

"This? This is a little instrument known as the audion, a wireless electric-wave detector."

"Outside the hull?" repeated Shirley, still dazed.

"Yes," cried Kennedy excitedly. "I got my first clue from that flickering Welsbach mantle last night. Of course it flickered from the wireless we were using, but it kept on. You know in the gas-mantle there is matter in a most mobile and tenuous state, very sensitive to heat and sound vibrations.

"Now, the audion, as you see, consists of two platinum wings, parallel to the plane of a bowed filament of an incandescent light in a vacuum. It was invented by Dr. Lee DeForest to detect wireless. When the light is turned on and the little tantalum filament glows, it is ready for business.

"It can be used for all systems of wireless—singing spark, quenched spark, arc sets, telephone sets; in fact, it will detect a wireless wave from whatever source it is sent. It is so susceptible that a man with one attached to an ordinary steel-rod umbrella on a rainy night can pick up wireless messages that are being transmitted within some hundreds of miles radius."

The audion buzzed.

"There—see? Our wireless is not working. But with the audion you can see that some wireless is, and a fairly near and powerful source it is, too."

Kennedy was absorbed in watching the audion.

Suddenly he turned and faced us. He had evidently reached a conclusion. "Captain," he cried, "can you send a wireless message? Yes? Well, this is to Burke. He is over there back of the hotel on the hill with some of his men. He has one there who understands wireless, and to whom I have given another audion. Quick, before this other wireless cuts in on us again. I want others to get the message as well as Burke. Send this: 'Have your men watch the railroad station and every road to it. Surround the Stamford cottage. There is some wireless interference from that direction.'"

As Shirley, with a half-insane light in his eyes, flashed the message mechanically through space, Craig rose and signalled to the house. Under the portecochere I saw a waiting automobile, which an instant later tore up the broken-stone path and whirled around almost on two wheels near the edge of the cliff. Glowing with health and excitement, Gladys Shirley was at the wheel herself. In spite of the tenseness of the situation, I could not help stopping to admire the change in the graceful, girlish figure of the night before, which was now all lithe energy and alertness in her eager devotion to carrying out the minutest detail of Kennedy's plan to aid her father.

"Excellent, Miss Shirley," exclaimed Kennedy, "but when I asked Burke to have you keep a car in readiness, I had no idea you would drive it yourself."

"I like it," she remonstrated, as he offered to take the wheel. "Please—please—let me drive. I shall go crazy if I'm not doing something. I saw the Z99 go down. What was it? Who—"

"Captain," called Craig. "Quick—into the car. We must hurry. To the Stamford house, Miss Shirley. No one can get away from it before we arrive. It is surrounded."

Everything was quiet, apparently, about the house as our wild ride around the edge of the harbour ended under the deft guidance of Gladys Shirley. Here and there, behind a hedge or tree, I could see a lurking secret-service man. Burke joined us from behind a barn next door.

"Not a soul has gone in or out," he whispered. "There does not seem to be a sign of life there."

Craig and Burke had by this time reached the broad veranda. They did not wait to ring the bell, but carried the door down literally off its hinges. We followed closely.

A scream from the drawing-room brought us to a halt. It was Mrs. Brainard, tall, almost imperial in her loose morning gown, her dark eyes snapping fire at the sudden intrusion. I could not tell whether she had really noticed that the house was watched or was acting a part.

"What does this mean?" she demanded. "What—Gladys—you—"

"Florence—tell them—it isn't so—is it? You don't know a thing about those plans of father's that were—stolen—that night."

"Where is Nordheim?" interjected Burke quickly, a little of his "third degree" training getting the upper hand.

"Nordheim?"

"Yes—you know. Tell me. Is he here?"

"Here? Isn't it bad enough to hound him, without hounding me, too? Will you merciless detectives drive us all from, place to place with your brutal suspicions?"

"Merciless?" inquired Burke, smiling with sarcasm. "Who has been hounding him?"

"You know very well what I mean," she repeated, drawing herself up to her full height and patting Gladys's hand to reassure her. "Read that message on the table."

Burke picked up a yellow telegram dated New York, two days before.

It was as I feared when I left you. The secret service must have rummaged my baggage both here and at the hotel. They have taken some very valuable papers of mine.

"Secret service—rummage baggage?" repeated Burke, himself now in perplexity. "That is news to me. We have rummaged no trunks or bags, least of all Nordheim's. In fact, we have never been able to find them at all."

"Upstairs, Burke—the servants' quarters," interrupted Craig impatiently. "We are wasting time here."

Mrs. Brainard offered no protest. I began to think that the whole thing was indeed a surprise to her, and that she had, in fact, been reading, instead of making a studied effort to appear surprised at our intrusion.

Room after room was flung open without finding any one, until we reached the attic, which had been finished off into several rooms. One door was closed. Craig opened it cautiously. It was pitch dark in spite of the broad daylight outside. We entered gingerly.

On the floor lay two dark piles of something. My foot touched one of them. I drew back in horror at the feeling. It was the body of a man.

Kennedy struck a light, and as he bent over in its little circle of radiance, he disclosed a ghastly scene.

"Hari-kiri!" he ejaculated. "They must have got my message to Burke and have seen that the house was surrounded."

The two Japanese servants had committed suicide.

"Wh-what does it all mean?" gasped Mrs. Brainard, who had followed us upstairs with Gladys.

Burke's lip curled slightly and he was about to speak.

"It means," hastened Kennedy, "that you have been double crossed, Mrs. Brainard. Nordheim stole those plans of Captain Shirley's submarine for his Titan Iron Works. Then the Japs stole them from his baggage at the hotel. He thought the secret service had them. The Japs waited here just long enough to try the plans against the Z99 herself—to destroy Captain Shirley's work by his own method of destruction. It was clever, clever. It would make his labours seem like a failure and would discourage others from keeping up the experiments. They had planned to steal a march on the world. Every time the Z99 was out they worked up here with their improvised wireless until they found the wave-length Shirley was using. It took fifteen or twenty minutes, but they managed, finally, to interfere so that they sent the submarine to the bottom of the harbour. Instead of being the criminal, Burke, Mrs. Brainard is the victim, the victim both of Nordheim and of her servants."

Craig had thrown open a window and had dropped down on his knees before a little stove by which the room was heated. He was poking eagerly in a pile of charred paper and linen.

"Shirley," he cried, "your secret is safe, even though the duplicate plans were stolen. There will be no more interference."

The Captain seized Craig by both hands and wrung them like the handle of a pump.

"Oh, thank you—thank you—thank you," cried Gladys, running up and almost dancing with joy at the change in her father. "I—I could almost—kiss you!"

"I could let you," twinkled Craig, promptly, as she blushed deeply. "Thank you, too, Mrs. Brainard," he added, turning to acknowledge her congratulations also. "I am glad I have been able to be of service to you."

"Won't you come back to the house for dinner?" urged the Captain.

Kennedy looked at me and smiled. "Walter," he said, "this is no place for two old bachelors like us."

Then turning, he added, "Many thanks, sir,—but, seriously, last night we slept principally in day coaches. Really I must turn the case over to Burke now and get back to the city to-night early."

They insisted on accompanying us to the station, and there the congratulations were done all over again.

"Why," exclaimed Kennedy, as we settled ourselves in the Pullman after waving a final good-bye, "I shall be afraid to go back to that town again. I—I almost did kiss her!"

Then his face settled into its usual stern lines, although softened, I thought. I am sure that it was not the New England landscape, with its quaint stone fences, that he looked at out of the window, but the recollection of the bright dashing figure of Gladys Shirley.

It was seldom that a girl made so forcible an impression on Kennedy, I know, for on our return he fairly dived into work, like the Z99 herself, and I did not see him all the next day until just before dinner time. Then he came in and spent half an hour restoring his acid-stained fingers to something like human semblance.

He said nothing about his research work of the day, and I was just about to remark that a day had passed without its usual fresh alarum and excursion, when a tap on the door buzzer was followed by the entrance of our old friend Andrews, head of the Great Eastern Life Insurance Company's own detective service.

"Kennedy," he began, "I have a startling case for you. Can you help me out with it?"

As he sat down heavily, he pulled from his immense black wallet some scraps of paper and newspaper cuttings.

"You recall, I suppose," he went on, unfolding the papers without waiting for an answer, "the recent death of young Montague Phelps, at Woodbine, just outside the city?"

Kennedy nodded. The death of Phelps, about ten days before, had attracted nation-wide attention because of the heroic fight for life he had made against what the doctors admitted had puzzled them—a new and baffling manifestation of coma. They had laboured hard to keep him awake, but had not succeeded, and after several days of lying in a comatose state he had finally succumbed. It was one of those strange but rather frequent cases of long sleeps reported in the newspapers, although it was by no means one which might be classed as record-breaking.

The interest in Phelps lay, a great deal, in the fact that the young man had married the popular dancer, Anginette Petrovska, a few months previously. His honeymoon trip around the world had suddenly been interrupted, while the couple were crossing Siberia, by the news of the failure of the Phelps banking-house in Wall Street and the practical wiping-out of his fortune. He had returned, only to fall a victim to a greater misfortune.

"A few days before his death," continued Andrews, measuring his words carefully, "I, or rather the Great Eastern, which had been secretly investigating the case, received this letter. What do you think of it?"

He spread out on the table a crumpled note in a palpably disguised handwriting:

TO WHOM IT MAY CONCERN:

You would do well to look Into the death of Montague Phelps, Jr. I accuse no one, assert nothing. But when a young man apparently in the best of health, drops off so mysteriously and even the physician in the case can give no very convincing information, that case warrants attention. I know what I know.

AN OUTSIDER.